an experiment in happiness
by Wagandea
Summary: Marty isn't thinking fourth-dimensionally. Slash.


( **A/N: Some knowledge of the games is required for this, but reading a summary should give you the info you need if you haven't played them.** )

* * *

"Time is like this," Doc, old universe Doc, is saying, turning an egg timer over in his calloused hands, sand flowing from end to end. "Continuously moving along, you see? Now, in an ideal world, nothing happens to the hourglass, and it keeps turning itself. Unfortunately, mishaps are unavoidable," he finishes gravely, and Marty's brow furrows in confusion.

"Okay, I kinda get where you're coming from Doc, but why-"

Doc holds up a finger to silence him, and lets go, the hourglass shattering on the concrete floor of the lab, sand and shards of glass spilling about Marty's feet. "What do you think we do if the unfortunate, as pictured on the floor currently, happens?"

"I'm... gonna guess you'll say something about how we have to sweep up the sand, right?" Marty starts dubiously, but Doc shakes his head, suddenly looking weary and old and tired. He smiles, all the same.

"No, Marty. We buy another egg timer."

* * *

"You just, _listen_ to me Emmett, you can't marry her okay?" he's saying desperately, but no amount of talking will change things and he knows that-and Marty gets the feeling that he's just making Emmett more frustrated by the minute, anyway.

"And I'm supposed to take your 'advice' why? Because you waltz in here and say so? You don't know Edna, and you certainly don't know me!" Emmett nearly shouts back, looking seconds away from pulling out his own hair.

Marty swallows, thickly, and all he can think is _come on, Doc, I know you better than you know yourself these days,_ except he doesn't because Doc is _gone_ , probably forever this time. The magnitude of the situation hits him then. Doc is gone and realistically speaking he's not coming back the way Marty remembers him even if they do fix this.

"Okay," Marty says, and hates the way his voice wavers just a little. "So maybe I don't know you, Emmett. But I _want_ to."

Emmett is all he has, in a screwed up sense. He realizes, now, what he has to do, and it _sucks_ , and while he's at it he wants to make sure Doc never even thinks the words 'time machine'.

The weight of that statement, the silence, settles over the lab like a thick blanket. Marty feels like suffocating but he presses forward, literally and figuratively. Emmett looks like the deer in the headlights, wide eyes flitting from side to side, looking for an escape route that doesn't exist.

"Hey, it's okay, look, you're okay, I just... gotta do something, before you go all crazy and decide to marry the first girl that gives you the time of day."

It occurs to him a little too late that Emmett doesn't even know what he's talking about, what Marty has to do. Maybe he thinks Marty's going to hit him, or... something like that, judging by the expression on his face, and _Christ, Doc's only a teenager_. It doesn't occur to Marty that he's one too.

"What do you possibly think you could do to change my mind?!" Doc-Emmett, Marty has to remind himself, still-protests, voice cracking. He's flush against the side of the lab table now and Marty keeps pushing forward.

I'm sorry, Marty's thinking, over and over, and maybe it's not that he's gotta- _defile_ Emmett, or whatever this is. Maybe it's that he, well, actually wants to. It's not even that he's gay, because he's never looked at the rest of the Pinheads funny, or any other guys in his school. It's _just_ Doc. That seems significant somehow.

"I can think of one or two things," Marty says, mouth going dry. He doesn't give Emmett a chance to ask what that means because Marty is kissing him, pressing him up against the edge of the lab table. It's chaste at first but Emmett freeezes, then leans desperately out of the kiss.

"Stop," he whispers hoarsely, panicked. Marty doesn't respond, hates himself for what he does next. His hand finds itself firmly on the back of Emmett's neck, pulls him in again.

* * *

His mom-Marty doesn't remember which Lorraine said it, and it bothers him more than it should how the memories are becoming indistinguishable from each other-once asked him if he felt safe around Doc Brown.

"Geez, mom. What, you think he's experimenting on me or something?" Marty quips back with an eye roll thrown in for good measure. "I told you, that time I got electrocuted was an accident, and Doc _told_ me to put on those rubber shoes, so technically it was my fault for not listening."

Lorraine just fixes him with that tired, worried look, and says slowly, "no, Marty, that's not what I mean."

But Marty _knows_ what she means, and that just... makes it so much worse. _It's not Doc_ , he wants to say, but doesn't. _It's me_.

He pulls a face, instead, before his mom has a chance to clarify herself. "Alright I get the picture! Ugh, that's just-Mom, you _know_ Doc. Just because he's lonely doesn't mean..." He stops, shakes his head. "The guys at school don't get it, you know? The science thing. It's _cool_ , and Doc gets that. Plus, he always needs help on his experiments, so... that's where I come in. That's it, the whole story. I promise."

Except it's not, but his mom doesn't need to know that, and hell, _Doc_ doesn't either. Marty's big gay secret is none but his own.

That doesn't seem to placate Lorraine much, but she drops it. In an overly casual tone, she says, "I didn't know you liked science so much, Marty."

"Yeah," Marty says, mouth going dry. "Neither did I."

* * *

It's 1931 and Emmett is kissing Marty back, clumsy and inexperienced like he's never kissed anyone, _really_ kissed anyone. Marty's doing all the work anyway, sliding his tongue against Emmett's in a way that's gotta be making him weak in the knees, if the way he's gripping the lab table for support is any indication.

Emmett lets off a low, almost panicked whine, and Marty pulls back just enough to break the kiss. He licks his lips nervously, and it doesn't escape him that Emmett's eyes follow the motion. Emmett, with his lips bruised red from the kiss and a matching flush of color settled heavy on his cheeks.

Emmett opens his mouth to say something, but can't get the words out right and his gaze keeps flitting from Marty's lips to his eyes and back down again.

"Is this okay?"

Marty's the one who breaks the silence, and despite what he's just done he can feel his hands trembling from nervousness. He tries to anchor them on Emmett's waist, but the taller boy pulls his hips back, sharply.

"I... this is-"

"Let me guess," Marty starts ruefully, "illegal, not to mention several flavors of messed up and just plain wrong? I get it, Emmett, I do. But something tells me you've never wanted anything like this from Edna."

Emmett doesn't seem to have a response to that, mouth closing abruptly. He turned slightly redder, this time more out of humiliation and embarrassment.

So it was true. Marty had his suspicions about Doc, yes, but for the most part he'd chalked it up to wishful thinking, despite the fact that up until Clara, he could count on one hand the number of conversations he'd witnessed Doc having with women. Most of them had been brief, awkward exchanges with Jennifer.

But he can't think about Jennifer right now, even the thought of her name threatens to make him sick to his stomach with guilt, because here he is _seducing_ the Doc, and the fact that he's cheating still hurts, even if he's not sure where Jennifer even fits in anymore.

He's so wrapped up in himself that it comes as a complete surprise when Emmett kisses him, and this time Marty's the one who freezes. It's awkward and a little surreal and he can't quite put his finger on it but it feels _important_ , the chaste press of lips because Emmett's too scared to go any further. Like a first kiss, a real first kiss.

It seems like hours before Emmett finally pulls back, an apology on his lips that's cut short because Marty's laughing. From nervousness or the sheer emotion of the situation he's not sure, but Emmett's making the same offended and impatient face Doc gives him, and Marty's thinking _some things never change_ -

His eyes are watery and it isn't from the laughter when he finally pulls himself together.

This is the moment history changes in any significant capacity. In another timeline, there is still much more to do; a plot to ruin the borrowed white suit, deliberate and immoral tinkering with Emmett's invention; a revelation of false infidelity. Then, the inevitable consequences of involving Citizen Brown.

Instead, Marty hears the thunderous lightning crack of the time machine outside the garage, the all too familiar sound of the DeLorean screeching to a halt. The noise is enough to distract Emmett for a split second, and Marty slips away.

"Hey, Emmett, I-" he starts to call out as he backs away towards the door, but stops, words failing him. It's a goodbye, he realizes, staring into Emmett's baffled face. Just not for him. "I gotta go," Marty starts again, voice soft, a little pained. "There's something I have to do." He's been saying that a lot lately. It probably sounds like a pretty lame excuse.

"Wait!" Emmett exclaims back, and steps forward, reaching a hand out desperately. "You can't just come in here and… and..." But Emmett's struggling with words too, and Marty can't blame him, considering that the last time Marty left with no notice, he was gone for months. It'll be longer this time.

"I'll see you again," Marty promises, desperately. "Don't forget me, alright?"

Ironically, it's Doc who's coming back for him now, rather than the other way around. Marty wonders what version it'll be this time, with a sinking feeling in his stomach and the image of eighteen year old Emmett, hurt and betrayed, burned into the back of his retinas.

The garage door slams shut behind him, and Marty jogs down the long driveway of the Brown estate to where the DeLorean is waiting. It's not Citizen Brown sitting in the driver's side like he expected though, and the uncomfortable feeling in his stomach makes way for a flood of relief when he makes eye contact with Doc, _his_ Doc-or at least, that's what it _looks_ like as far as he can tell-through the windshield.

The passenger door is already open, waiting for him, and Marty sides onto the leather seat, pulling the door down shut. He feels like he can finally take a breath, have a moment to himself without worrying about the past, or the future, or anywhere inbetween.

"Where to now, Future Boy?" Doc asks, hand on the gear shift, and his tone indicates that he's only teasing, but Marty groans.

"Oh _God_ , Doc, please tell me you're joking," he complains, eyes squeezed shut. "I've done enough time-traveling for one lifetime."

"Or four or five," Doc suggests lightly, the corners of his eyes crinkling up in a smile. He reaches over and squeezes Marty's thigh in what's probably supposed to be reassurance, but just comes across as… kinda weird, if Marty thinks too hard about it. Uneasily, he figures it's just one of Doc's odd gestures that don't mean anything near what Marty thinks they mean.

Except, he's not sure anymore, not with what he just _did_ in the lab. It's only _now_ , reaching 75 miles per hour and climbing, that Marty gives consideration to the idea that he probably changed the future in other ways than Doc not marrying Edna when he made the decision to kiss Emmett in 1931. They hit 88 before he can fully start to ponder the consequences of his actions.

* * *

Doc suggests he spend the night at the garage (which isn't being sold off in this timeline, thankfully), but ultimately ends up dropping Marty off at his house, with Marty reasoning that knowing his luck, he needs to check up on his family to make sure he didn't screw anything up when he was in the 30s.

He lucks out, just this once. The house looks exactly the same as it did when he left. The same leftovers are in the fridge, which satisfies his desire to make sure the timeline's intact again. Mom's off with friends and Dad's holed up in his study writing anyway. Marty briefly entertains the idea that maybe he should have stayed over at Doc's after all, but then he remembers kissing Emmett in the lab, remembers Doc's hand on his thigh in the car-

He feels sick as soon as he connects the two, nervous and bothered and hot under the collar. It's only 9:30 but Marty wants the day to be over, wants to stop thinking about Doc, wants to stop thinking about anything.

He gets ready for bed on autopilot, mind whirring. The world doesn't make sense anymore, but maybe it will in the morning, maybe this is just the end of a really confusing dream.

Marty's real dreams turn out to be more confusing, too vivid and hyper-realistic, every detail of Doc's garage perfectly in place, but he can't hear what Doc's trying to tell him because he's too focused on Doc's mouth, his hands. The scene changes. He dreams he's pushing Emmett up against the lab table again, the kisses slick and heavy and the boy's mouth hot and inviting, except Marty's hands are balled up in the fabric of an old hawaiian shirt instead of a sweater vest, which is odd but somehow doesn't tip off his dream self. It's when reaches into Emmett's boxers, fingers moving to awkwardly stroke his cock, that he realizes Emmett isn't seventeen this time. The scene changes and Marty's still in the lab, completely naked and lounging face down on the worn out couch while a hand, cold and slick with something, moves softly between his legs, and Doc's above him, saying-

 _"Marty, please tell me if this gets uncomfortable for you-"_

-and it's not his own words leaving his mouth but Marty says them anyways, says _"oh God, Doc, please-"_

He's jolted awake to his alarm with possibly the worst hard on he's ever had, and it takes an embarrassingly long second for Marty to realize he's at home, alone, in his own bed, and has never had sex with Doc Brown.

And while he doesn't like to admit it, it's not the first time he's had dreams like this about Doc, but hey, people have weird sex dreams all the time, right? It was just at this time felt different, tangible somehow, more like a memory than a dream.

Marty bites his lip and reaches his hand under the covers, trying, _trying_ to think about anything besides the too-real feeling of Dream-Doc's fingers in his ass, nevermind the fact that he knew next to nothing about what gay sex might entail before the dream.

He's looking for a clean pair of underwear when he finds what he's pretty sure are condoms in his bedside dresser. He doesn't remember buying them, has never had a reason to.

* * *

School passes inexplicably slowly, and Marty spends most of his classes staring at the clock. He feels jumpy, paranoid, which is stupid and he _knows_ that, but it doesn't stop him sweating every time someone looks at him too long, because he can't stop thinking about Doc's mouth, his hands, and he feels like it's plastered on his face, a giant neon sign saying "I'm Gay, Come And Get Me!" Someone has to say something. No one does.

Mostly he just feels dirty. His feet automatically take him to Doc's after school anyway, a ritual he no longer thinks about.

He stands outside the garage for 20 minutes without knocking, and ends up going home before Doc can find him instead.

* * *

It's not that Marty's _scared_ of his best friend, or of facing him, except maybe he is a little, and he doesn't know how to feel about that. He doesn't know how to feel about any of it, because yeah he was crushing on Doc before going to 1931, but it always just felt _wrong_ , like he was a freak for having those feelings at all, let alone considering acting on them.

So it does scare him, that all the evidence is pointing to this timeline's Marty and Doc as something other than _just friends_. It scares him even more that it's all his fault, that if he'd just bothered to think of some other way, any other way to break up Emmett and Edna, things wouldn't have changed between them.

* * *

Still, despite his suspicions being technically unconfirmed, it takes Marty another three days to break down and go over to Doc's properly this time. Missing his best friend triumphs over not wanting to confront the truth, he guesses. Maybe his priorities are just all screwed up.

Doc answers the door in ratty old pajamas and a bathrobe. The first thing he does is squint at surprise in the sun and check his watch. The second thing he does is turn his attention to Marty and look at him with such enthusiasm and happiness that Marty can't help but feel instantly guilty.

"Marty!" he exclaims, as enthusiastic as ever, and quickly steps back from the door to usher Marty inside. "Come in, come in, I was just about to fix a sandwich for dinner-or, breakfast I suppose. Is it really that early? Nevermind that, are you hungry?"

"Uh. Not really," Marty manages awkwardly, and closes the door behind himself but doesn't make any effort to move out of the makeshift entryway or make himself comfortable.

Unsurprisingly, Doc takes notice immediately and he's peering at Marty with genuine concern. "Did something happen?"

"No! Well, _yes_ , but…" He shuffles his feet awkwardly, and it takes him a moment to figure out what to say. When he does it comes out strained, halting. "I uh, I don't think I came back the same that you remember me, Doc. I mean, I think I'm from a really different timeline than your Marty-I mean, the Marty you know."

The concern on Doc's face gives way for curiosity and understanding. He makes for the threadbare couch, and motions for Marty to join him. He does, reluctantly, and has to push the memory of the dream starring the couch and Doc's fingers out of the way.

"What differences have you observed between this timeline and your own? Is your family-"

"It's not my family," Marty interjects quickly, and bites his lip while he figures out how to proceed. "Look, in my timeline we're best friends Doc, the best okay?" he starts, but Doc just looks bewildered now, like he's not sure why Marty is even bringing this up.

"Well of course!" he exclaims, more confused by the second. "You can't believe that's changed, have you? I assure you, Marty, there's nothing to worry about, you're the closest friend I've had."

 _Yeah_ , Marty thinks glumly. _That's kind of the problem._ "I mean, we're _just friends_ , Doc. But in this timeline, have we… y'know…?" he trails off, too uncomfortable to just come out and say it, hoping Doc catches the full implications of that _y'know_. Judging by the dawning understanding on his face, he does.

This time it's Doc who's struggling for words. "I assume," he begins tentatively, something about his tone implying he's trying to be extra careful with the words. Marty appreciates the thought, even if he feels like he'll never be ready for what comes next. "That in your timeline, our emotional bond doesn't extend past friendship?"

Marty just stares at him in vague confusion, because that's… well, that's not what he was expecting Doc to say. It's not like he was asking if they were in a _relationship_ , because that didn't happen, right? From what he'd heard about the gay thing, which admittedly wasn't a lot, it was just some… weird sex thing. He has in inkling, now, that maybe he's been approaching this from the wrong angle.

"Um. Well, uh, you're… you've got Clara and the kids, so..." he offers weakly, face hot with embarrassment, and if Marty could just sink into the couch cushions and disappear forever that would be great.

Clara. Right, Clara, now that he thinks about it, Doc hasn't said _anything_ about Clara or Jules and Verne, and now that he thinks about it, it's _really_ weird that he's here alone. "Where are they, anyway? I don't want to steal you away from your family, Doc-uh, I mean, I mean, I should. Probably just get going."

Doc's eyebrows shoot so high up his forehead they're threatening to disappear into his hairline. "Clara?" he asks with such bewilderment that Marty's heart sinks. He was jealous and a little bitter, yeah, but they were… they were _happy_. He can't help but feel like in this timeline at least, he robbed Doc of that. "The schoolteacher? From 1885?"

Marty can only nod, unable to even start to think about what he'd say, how to compress everything that's happened since 1885 into an explanation, everything that now is just… gone, wiped clean. It never existed.

But Doc is a genius and maybe he doesn't need explaining, because his eyebrows are shooting so far up his forehead that they might just disappear into his hair. "Incredible!" he exclaims, equal parts taken aback and mystified. "I never thought of Clara as more than a friend, given that I was already attached at the time I met her. And never have I considered starting a family, it just isn't possible for this version of myself! Marty, considering the differences from your timeline to mine, it would be wise for us to talk these differences over. I'm aware you've already made some assumptions on the nature of our relationship, which are likely correct, but I want to make it clear to you that I don't wish to make you uncomfortable, and that I value your friendship over anything else. If our intimate relationship bothers you, I would gladly-"

"-a history lesson would be nice, yeah," Marty cuts in, letting Doc talk until he can't stand it anymore. He's uncomfortable and he's nervous but the possibility of… being gay with his best friend, being in a relationship with him, doesn't bother Marty the way it should.

He thinks about the hourglass, shattering on the garage floor. Thinks about Jennifer and Clara, thinks about kissing Emmett in 1931 and about Doc touching him on the couch in the dream. It's time to buy a new egg timer.

It takes all of Marty's courage to reach over and grab Doc's hand, giving it a comforting squeeze that's more for his benefit than Doc's.

 _Take it slow, McFly._

And basic hand-holding isn't what he really needs or wants, but it's enough for now. It has to be.


End file.
